LOGICAL FALLACIESLOGICAL FALLACIES

What are logical fallacies?What are logical fallacies?

When trying to make a case or When trying to make a case or argument where logic is missing or argument where logic is missing or something in the case is not clearsomething in the case is not clear

Is not necessarily a false statementIs not necessarily a false statement Can be useful in debatesCan be useful in debates

Why learn logical fallacies?Why learn logical fallacies?

Point them out when an opponent uses one Point them out when an opponent uses one or offer reasoning if you use themor offer reasoning if you use them

Make you look smartMake you look smart Impresses judgesImpresses judges Can remove an argument from the table Can remove an argument from the table

not just weaken itnot just weaken it You can know when you are using them and You can know when you are using them and

prepare for your opponents argument prepare for your opponents argument rather than being taken off guard and rather than being taken off guard and unpreparedunprepared

How do you point them out?How do you point them out?

State the name of fallacy in Latin and English State the name of fallacy in Latin and English making sure to use the phrase “logical fallacy”making sure to use the phrase “logical fallacy”

Tell everyone what the fallacy means and why it Tell everyone what the fallacy means and why it is wrong but do it without sounding pedantic is wrong but do it without sounding pedantic (smarter than everyone else)(smarter than everyone else)

Give a really obvious example of why the fallacy Give a really obvious example of why the fallacy is incorrect, preferably the example should also is incorrect, preferably the example should also be an unfavorable analogy for your opponents be an unfavorable analogy for your opponents casecase

Point out why the fallacy matters to the debate Point out why the fallacy matters to the debate roundround

Argumentun ad Argumentun ad antiquitatemantiquitatem

The argument to antiquity or traditionThe argument to antiquity or tradition Argument that a policy, behavior or practice is Argument that a policy, behavior or practice is

right or acceptable because “its always been right or acceptable because “its always been done that way”done that way”

Example: “every great civilization in history has Example: “every great civilization in history has provided states subsidies for art and culture”provided states subsidies for art and culture”

Try to avoid it but if you do use it, try to give a Try to avoid it but if you do use it, try to give a reason why it should be consideredreason why it should be considered

Argumentum ad hominemArgumentum ad hominem

Argument directed at the personArgument directed at the person Attacking the character or motives of a person Attacking the character or motives of a person

who has stated and idea rather than the idea who has stated and idea rather than the idea itself; can also be an attack on the source of itself; can also be an attack on the source of informationinformation

““my opponents are fascists” or “Richard Nixon my opponents are fascists” or “Richard Nixon was liar and a cheat”was liar and a cheat”

Can also be used when the person talking has Can also be used when the person talking has something to gain from the policy (example: something to gain from the policy (example: Bill Gates talking against anti-trust legislation)Bill Gates talking against anti-trust legislation)

Argumentum ad Argumentum ad ignorantiamignorantiam

Argument to ignoranceArgument to ignorance Assuming something is true simple because it Assuming something is true simple because it

hasn’t been proven false (example: global hasn’t been proven false (example: global warming is true because nobody has warming is true because nobody has demonstrated conclusively it is not)demonstrated conclusively it is not)

Which ever team/person has “burden of proof” Which ever team/person has “burden of proof” (usually affirmative) has to be more careful in (usually affirmative) has to be more careful in using this fallacyusing this fallacy

Example: Prosecution who says that no alibi Example: Prosecution who says that no alibi means guilty vs.. Defense saying prosecution means guilty vs.. Defense saying prosecution didn’t prove case so defendant is not guiltydidn’t prove case so defendant is not guilty

Argument ad logicamArgument ad logicam

Argument to logicArgument to logic Assuming that something is false simply because Assuming that something is false simply because

proof or argument that someone has offered for it is proof or argument that someone has offered for it is invalidinvalid

Also known as Straw Man argumentAlso known as Straw Man argument Burden of proof determines whether it is fallacy or not Burden of proof determines whether it is fallacy or not

(if affirmative team fails to provide sufficient support (if affirmative team fails to provide sufficient support for its case, the burden of proof dictates they should for its case, the burden of proof dictates they should lose the debate even if there exist other arguments lose the debate even if there exist other arguments not presented that could have supported the case)not presented that could have supported the case)

Argumentum ad Argumentum ad misericordianmisericordian

Argument or appeal to pityArgument or appeal to pity Example: “Think of all the poor, starving Example: “Think of all the poor, starving

people in Ethiopia. How can we not help people in Ethiopia. How can we not help them?”them?”

This doesn’t mean you can’t argue for This doesn’t mean you can’t argue for something like aid to Ethiopia, what it something like aid to Ethiopia, what it does mean is that you can’t just use does mean is that you can’t just use emotional pleasemotional pleas

Do not use it unless the opposition has Do not use it unless the opposition has ONLY offered emotional pleasONLY offered emotional pleas

Argumentum ad nauseamArgumentum ad nauseam

Argument to the point of disgust Argument to the point of disgust (repetition)(repetition)

Trying to prove something by saying it Trying to prove something by saying it again and againagain and again

Stating a main point over and over again Stating a main point over and over again instead of real argumentsinstead of real arguments

Make sure you SUPPORT your main pointsMake sure you SUPPORT your main points

Argumentum ad numerumArgumentum ad numerum

Argument or appeal to numbersArgument or appeal to numbers Attempt to prove something by Attempt to prove something by

showing how many people think that showing how many people think that it’s trueit’s true

Example: 70% of all Americans Example: 70% of all Americans support restrictions on access to support restrictions on access to abortionsabortions

Don’t confuse this with argumentum Don’t confuse this with argumentum ad populumad populum

Argumentum ad populumArgumentum ad populum

Appeal to people or to popularityAppeal to people or to popularity Trying to prove something by Trying to prove something by

showing that the public agrees with showing that the public agrees with youyou

Narrowly designates an appeal to the Narrowly designates an appeal to the opinions of people in the immediate opinions of people in the immediate vicinity like your judgesvicinity like your judges

Argumentum ad Argumentum ad verecundiamverecundiam

Argument or appeal to authorityArgument or appeal to authority Someone tries to demonstrate the truth of Someone tries to demonstrate the truth of

a proposition by citing some person who a proposition by citing some person who agrees, even though that person may agrees, even though that person may have no expertise in the given areahave no expertise in the given area

Example: Quoting Einstein on politicsExample: Quoting Einstein on politics Only use this when they don’t use Only use this when they don’t use

qualified quotes to support the same point qualified quotes to support the same point and/or imply some policy is right because and/or imply some policy is right because so-and-so thought soso-and-so thought so

Circulus in demonstrandoCirculus in demonstrando

Circular argumentCircular argument Someone uses what they are trying Someone uses what they are trying

to prove as part of the proof of that to prove as part of the proof of that thingthing

Always illegitimate but hard to spotAlways illegitimate but hard to spot

Complex QuestionComplex Question

Question that implicitly assumes Question that implicitly assumes something to be true by its constructionsomething to be true by its construction

Example: Have you stopped beating your Example: Have you stopped beating your wife” or “Inasmuch as the majority of wife” or “Inasmuch as the majority of black Americans live in poverty, do you black Americans live in poverty, do you really think that self-help within the black really think that self-help within the black community is sufficient to address their community is sufficient to address their problems?”problems?”

Only a fallacy when used for something Only a fallacy when used for something that hasn’t been provedthat hasn’t been proved

Cum hoc ergo propter hocCum hoc ergo propter hoc

With this, therefore because of thisWith this, therefore because of this Mistaking correlation for causation Mistaking correlation for causation

(because two things occur simultaneously, (because two things occur simultaneously, one must be a cause of the other)one must be a cause of the other)

Example: President Clinton has great Example: President Clinton has great economic policies, just look at how great economic policies, just look at how great the economy isthe economy is

Usually called post hocUsually called post hoc

Dicto simpliciterDicto simpliciter

Sweeping generalizationSweeping generalization Making a sweeping statement and expecting Making a sweeping statement and expecting

it to be true of every specific case; aka it to be true of every specific case; aka “stereotyping”“stereotyping”

Example: Women on average are not as Example: Women on average are not as strong as mean and less able to carry a gun. strong as mean and less able to carry a gun. Therefore women can’t pull their weight in a Therefore women can’t pull their weight in a military unit.military unit.

When pointing it out in a round, try not to use When pointing it out in a round, try not to use the Latin and just attack the generalization the Latin and just attack the generalization

Nature, appeal toNature, appeal to

Assuming that whatever is natural or Assuming that whatever is natural or consistent with nature is good or that consistent with nature is good or that whatever conflicts with nature is badwhatever conflicts with nature is bad

Fairly rare, but usually seen in Fairly rare, but usually seen in environmentalist argument environmentalist argument

Naturalistic FallacyNaturalistic Fallacy

Trying to derive conclusions about what is Trying to derive conclusions about what is right or good (about values) from right or good (about values) from statements of fact alonestatements of fact alone

Any inference of fact is another fact NOT a Any inference of fact is another fact NOT a valuevalue

““The medicine will prevent you from The medicine will prevent you from dying” does not lead to ‘you should take dying” does not lead to ‘you should take this medicine”this medicine”

Examples include argumentum ad Examples include argumentum ad antiquities or appeal to natureantiquities or appeal to nature

Non SequiturNon Sequitur

It does not followIt does not follow Stating as a conclusion, something that Stating as a conclusion, something that

does not strictly follow from the premisesdoes not strictly follow from the premises Example: Racism is wrong, therefore, we Example: Racism is wrong, therefore, we

need affirmative action”need affirmative action” Try to to use this for every argument but Try to to use this for every argument but

use it when the opposition is trying to use it when the opposition is trying to construct A lead to B leads to C without construct A lead to B leads to C without justifying each step in the chainjustifying each step in the chain

Petitio PrincipiiPetitio Principii Begging the questionBegging the question Assuming, when trying to prove something, what it Assuming, when trying to prove something, what it

is that your are trying to proveis that your are trying to prove Very similar to circular argumentVery similar to circular argument Occurs when a question has been asked before in Occurs when a question has been asked before in

the discussion then a conclusion is reached on a the discussion then a conclusion is reached on a related matter without the question having been related matter without the question having been answeredanswered

Example: “The fact that we believe pornography Example: “The fact that we believe pornography should be legal means that it is valid form of free should be legal means that it is valid form of free expression. And since it’s free expression, it expression. And since it’s free expression, it shouldn’t be banned”shouldn’t be banned”

Post hoc ergo propter hocPost hoc ergo propter hoc

After this, therefore because of thisAfter this, therefore because of this Assuming that A caused B simply because Assuming that A caused B simply because

A happened prior to BA happened prior to B Example: most rapists read pornography Example: most rapists read pornography

when they were teenagers; obviously, when they were teenagers; obviously, pornography causes violence toward pornography causes violence toward women.women.

Similar to cum hoc ergo prompter hocSimilar to cum hoc ergo prompter hoc

Red herringRed herring

Introducing irrelevant facts or arguments Introducing irrelevant facts or arguments to distract from the question at handto distract from the question at hand

Example: The opposition claims that Example: The opposition claims that welfare dependency leads to higher crime welfare dependency leads to higher crime rates - but how are poor people supposed rates - but how are poor people supposed to keep a roof over their heads without our to keep a roof over their heads without our help?help?

It is not fallacious to argue that benefits of It is not fallacious to argue that benefits of one kind may justify incurring costs of one kind may justify incurring costs of another kindanother kind

Slippery slopeSlippery slope

Not always a fallacyNot always a fallacy Argument that says adopting one policy or Argument that says adopting one policy or

taking one action will lead to a series of taking one action will lead to a series of other policies or actions also being taken other policies or actions also being taken without showing a causal connection without showing a causal connection between the advocated policy and the between the advocated policy and the consequent policiesconsequent policies

Example: If we legalize marijuana, the Example: If we legalize marijuana, the next thing you know we’ll legalize heroin, next thing you know we’ll legalize heroin, LSD and crack cocaine.LSD and crack cocaine.

Straw manStraw man

Refuting a caricatured or extreme Refuting a caricatured or extreme version of somebody’s argument version of somebody’s argument rather than the actual argument rather than the actual argument they’ve madethey’ve made

Putting words into someone else’s Putting words into someone else’s mouth or misinterpreting something mouth or misinterpreting something saidsaid

Tu quoqueTu quoque

You tooYou too Defending an error in one’s reasoning by Defending an error in one’s reasoning by

pointing out that one’s opponent has pointing out that one’s opponent has made the same errormade the same error

Example: They accuse us of making Example: They accuse us of making unjustified assertions. But they asserted a unjustified assertions. But they asserted a lot of things, too.lot of things, too.

Can be helpful if both sides have done a Can be helpful if both sides have done a bad job of debating and you want to point bad job of debating and you want to point that out to the judgesthat out to the judges